We used a substitutive design to test the effects of eelgrass (Zostera marina) genotypic identity (eight genotypes), diversity (monocultures of 1 genotype vs. polycultures of 4 genotypes), and temperature (ambient or + 3.2° C) on the prevalence and intensity of Labyrinthula over eight weeks in an array of flow-through 120-L mesocosms at the Bodega Marine Laboratory in Bodega Bay, CA. We assigned ten pots - two unique polyculture combinations and each of the eight monocultures - to each of ten mesocosms, with five mesocosms per temperature treatment (see DuBois et al. 2020 for a diagram of the experimental set up). All mesocosms received sand-filtered flow-through seawater at a rate of approximately 0.8-1.0 L min^-1. We allowed the plants to acclimate for one month prior to initiating the temperature treatments. We maintained an ambient temperature treatment by cooling flow-through seawater in a head tank by approximately 1˚C using an Aqua Logic Delta Star in-line titanium chiller. Seawater in the elevated temperature treatment was raised approximately 3˚C above the ambient treatment in a separate header tank using Process Technologies titanium immersion heaters. This level of warming mimicked the 2014-15 extreme warming events in the Northern Pacific called “The Blob”, which raised summer ocean temperatures three standard deviations above the long-term average (Sanford et al. 2019).

Life Sciences Identifiers (LSID) for taxonomic names:
Zostera marina (urn:lsid:marinespecies.org:taxname:145795)
Labyrinthula zosterae (urn:lsid:marinespecies.org:taxname:395093)
Labyrinthula (urn:lsid:marinespecies.org:taxname:119090)

temp.csv